1. Field of the Invention
In general, the present invention relates to apparatus for separating from a mixture objects having a relatively low specific gravity from objects having a relatively high specific gravity, the objects within the mixture being heavier than water. The invention particularly relates to an immersion sorting apparatus useful for washing harvested potatoes and for removing rocks, debris, and adhering materials from the potatoes.
2. Description of the Prior Art
Due to the nature of the environment in which the useful portion of a potato plant naturally grows, potatoes, rocks, soil and debris are inevitably mixed during harvest. It is therefore necessary to remove the rocks and debris from the potatoes before the potatoes can be graded or processed. Since operationally effective and economically feasible sorting apparatus have not previously been available, rocks and debris are generally removed, particularly in the relatively smaller potato harvesting operations, by manual sorting operations. As is apparent, such manual operations are expensive and time consuming. While rocks and other debris can be separated from potatoes at a processing plant it is desirable to separate the potatoes from the associated debris prior to transport of the potatoes to the processing plant in order to limit damage to the potatoes while in transport. Therefore, it is desirable to effect sorting and washing operations as near to the harvesting operation as is possible. Therefore, the rocks and debris associated with and mixed with harvested potatoes must be removed in an economical manner as soon as is practical after harvesting in order to prevent damage to the potatoes during transport and to allow for immediate processing of the potatoes on arrival at a processing plant, it being an absolute necessity to remove rocks and similar debris from the potatoes before processing in order that processing equipment not be damaged.
Schoeneck, in U.S. Pat. No. 2,990,064, discloses an apparatus for washing potatoes and sorting the potatoes from rocks and other debris. In the Schoeneck apparatus, a flow of water caused to move downwardly along an inclined plane in a wash tank moves the lighter potatoes faster and thus further within the wash tank than the heavier rocks are caused to be moved, the potatoes thereby being separated from the rocks and removed from the wash tank at a location downstream of the flow of water. Lapeyre, in U.S. Pat. No. 3,421,620, discloses an apparatus for separating an undesired heavier component of a mixture of materials from a lighter desired component by placing the mixture in a liquid bath, the mixture being first lifted and then moved over a trap whereby the heavier of the two components settles out of the mixture into the trap by gravitation, the lighter component passing over the trap and thereby being separated from the heavier component. While the devices of the prior art as represented by Schoeneck and Lapeyre have found utility in the art, the present apparatus provides a mechanically compact, economically advantageous apparatus particularly intended for removal of rock and associated debris from harvested potatoes, a stream of water being directed against the mixture of potatoes and rock in a water bath as the mixture is caused to move over an opening formed in an inclined baffle member, the lighter potatoes being deflected past the opening to a first conveyor for removal from the water bath. The heavier rocks fall through the opening to a second conveyor for discharge from the bath.